1. Field of the Invention
The present invention relates to a robot controller, and more particularly relates to a robot controller in which a portable instruction and operating part comprising emergency stop operating means that place the robot in an emergency-stop state and emergency stop release operating means that release this emergency-stop state is connected by wireless communications with an control part that controls the robot.
2. Description of the Related Art
The connection of a portable teaching operating part equipped with an emergency-stop button or the like as emergency stop operating means used to cause emergency stopping of a robot, and a control part used to control the robot, by means of wireless communications, so that the operator can cause emergency stopping of the robot by operating the emergency-stop button or the like installed in the portable teaching operating part, is a conventionally known technique, and is disclosed for example in Japanese Patent Application Laid-Open No. H11-73201 and Japanese Patent Application Laid-Open No. H9-117888.
First, in Japanese Patent Application Laid-Open No. H11-73201, a communications system is disclosed in which the exchange of data between a robot control part (first device) and a robot teaching box (second device) is accomplished by wireless communications or optical communications. In this communications system, the robot control part (first device) and the teaching box (second device) are respectively provided with a transmitting part and a receiving part. Furthermore, the system is constructed so that the receiving part and transmitting part of the teaching box (second device) respectively handle the reception of data from the robot control part (first device) and the transmission of specified data as a response to this received data under normal conditions, but so that this response is stopped under abnormal conditions.
In this technique, the robot control part can ascertain the occurrence of an abnormality by the fact that there is no response from the teaching box, and can cause emergency stopping of the robot. Furthermore, in cases where trouble occurs in the teaching box as well, a tentative failsafe function is ensured by the lack of a response.
Specifically, compared to a system in which a signal indicating an abnormality is transmitted to the robot control part from the teaching box in the case of an abnormality, the possibility of avoiding a state in which “the transmission of an indication of an abnormal state to the robot control part becomes impossible because of trouble in the teaching box” is increased, so that the function of preserving the safety of the operator is correspondingly heightened.
Next, in Japanese Patent Application Laid-Open No. H9-117888, a remote operating system is disclosed in which communications are performed with the control part of a robot (movable part used for operation and object of control having driving means that drive this movable part) using a remote control transmitter which has a driving control switch and a control enabling switch operated by manual operation.
In this remote operating system, in a state in which the abovementioned control enabling switch has been operated, a base signal is continuously transmitted to the control part of the robot. On the other hand, when the abovementioned driving control switch is operated, a corresponding driving control signal is transmitted to the control part of the robot.
Furthermore, it is indicated that in the robot control part, the robot is controlled in accordance with the abovementioned driving control signal that is received only while the abovementioned base signal is being received at specified time intervals; when the abovementioned base signal is cut of, the robot is stopped regardless of whether a driving control signal is received or not. In this system as well, a failsafe function against trouble in the remote control transmitter is tentatively ensured by making the periodic reception of the base signal a condition for the driving of the robot.
However, in both of these conventional techniques, as was described above, only a single circuit for stopping the robot is provided. Accordingly, although consideration is given to safety in cases where wireless communications are cut off, no countermeasures are provided for cases in which it becomes impossible to stop the robot because of trouble in the circuit that stops the robot.